Solid dispersion technology as a strategy to improve the bioavailability of poorly soluble drugs

A new coamorphous ethionamide with enhanced solubility: Preparation, characterization, in silico pharmacokinetics, and controlled release by encapsulation

This study reports the synthesis and the experimental-theoretical characterization of a new coamorphous system consisting of ethionamide (ETH) and mandelic acid (MND) as a coformer. The solid dispersion was synthesized using the slow solvent evaporation method in an ethanolic medium. The structural, vibrational, and thermal properties of the system were characterized. Density functional theory (DFT) calculations were performed to analyze the interactions between ETH and MND in the heterodimer. These results contributed to the suitable assignment of infrared (IR) vibrational modes, to determine the chemical reactivity descriptors and the electronic indices of each component of the molecule. Additionally, Hirshfeld surfaces analysis and calculations of absorption, distribution, metabolism, and excretion (ADME) parameters were performed to examine intermolecular interactions and predict the in silico pharmacokinetic profile of the ETH-MND compound and its forming molecules. Powder X-ray diffraction data confirmed the formation of a coamorphous binary system in the 1:2 and 1:3 ETH and MND ratios. Furthermore, the ETH-MND (1:3) solid dispersion remained amorphous for up to 150 days when stored at 38 °C and 75 % relative humidity. DFT calculations, conducted both in vacuum and in ethanol, indicated that the formation of the coamorphous system is driven by hydrogen bonding between the NH2 groups of ETH and the C=O group of MND. Thermodynamic analysis showed that intermolecular interactions are favored in the gas phase, with Gibbs free energy of -3.20 kcal/mol. The IR spectra showed a correlation between experimental and calculated data. Thermal analyses revealed glass transition temperatures of 59 °C (1:2 ratio) and 61 °C (1:3 ratio), indicating thermal stability of the coamorphous materials. Additionally, dissolution tests showed a 3.58-fold increase in the solubility of ETH compared to its crystalline form. The encapsulation of ETH-MND coamorphous systems in sodium alginate spheres via polyelectrolyte complexation was also investigated, demonstrating significant controlled drug release over 480 min.

Enhanced dissolution and antibacterial potential of cinacalcet hydrochloride via ternary solid dispersions

Cinacalcet hydrochloride (HCl), a calcium-sensing receptor agonist used to treat hyperparathyroidism, suffers from poor solubility, reducing its bioavailability. Recently, cinacalcet HCl has been probed for repurposing as antibacterial agent. This work investigates cinacalcet HCl's potential as an antibacterial agent and provides a formulation to improve the drug dissolution. Solid dispersion formulations using Poloxamer 407, with and without Soluplus®, were prepared via solvent evaporation and hot melt congealing methods. The resulting formulations were analyzed using differential scanning calorimetry, FTIR spectroscopy, X-ray powder diffraction, and dissolution studies. These formulations significantly enhanced cinacalcet HCl dissolution compared to the unprocessed form, achieving up to a 15-fold increase in Q5 (percent of cinacalcet HCl dissolved after 5 min). The dissolution efficiency rose from 28% for the pure drug to 94.8 and 87.8% for formulations F6 and F7, respectively. Microbiological evaluations confirmed the antibacterial effect of cinacalcet HCl, which was notably increased in the Poloxamer 407 and Soluplus® hybrid formulation (F7) with a MIC of 64-128 µg/ml. Antibiofilm activity was also observed, with qRT-PCR indicating downregulation of biofilm genes (icaA, icaD, and fnbA). This study introduces a cinacalcet HCl formulation prepared using a scalable, green approach, demonstrating significant potential for antimicrobial applications.

In vivo pharmacokinetic study and PBPK modeling: Comparison between 3D-printed nanocrystals and solid dispersions

The solubility of drugs remains one of the most challenging aspects of formulation development. Several technologies exist to enhance the properties of poorly soluble drugs, with nanocrystal (NC) and solid dispersion (SD) technologies being among the most important. This work compared NCs and SDs under identical conditions using albendazole as a model drug and 3D printing technology as the delivery method. SDs were initially prepared and characterized, and then compared to the NCs system. Techniques such as TGA, DSC, XRD, FTIR, SEM, and confocal Raman microscopy were employed to assess the solid-state properties and formulation homogeneity. Solubility and dissolution profiles were evaluated under simulated gastric and intestinal conditions. An in vivo pharmacokinetic study was performed in dogs comparing 3D-printed formulations (NC-3D and SD-3D) with a control group treated with the pure drug (ABZ-C). A PBPK model was developed also in dogs to further analyse the results. While no statistically significant differences were observed in the in vitro dissolution profiles in 0.1 N HCl, differences emerged in precipitation time and solubility at intestinal pH (6.8). The pharmacokinetic study revealed improvements in the pharmacokinetic profile of both systems compared to the control, as expected. Between the NCs and the SD, the NC system demonstrated significantly superior pharmacokinetic parameters of interest. The PBPK model helped to explain the differences observed in the in vivo study. The results suggest that nanocrystal technology is more effective at enhancing the in vivo performance of Class II drugs, at least when using albendazole as the model drug.

Preparation, characterization, and ex vivo evaluation of isoxanthohumol nanosuspension

This study assessed the equilibrium solubility, oil-water distribution coefficient, and dissociation constant of Isoxanthohumol (IXN), and formulated IXN nanoparticles (IXN-Nps) using a micro media grinding method. The research characterized the particle size, polydispersity index, zeta potential, morphology, and structure of the nanoparticles, and evaluated the optimal cryoprotectant. Additionally, the study examined the toxicity and in vitro and in vivo release of IXN on HT-29 cells. IXN is classified as a Biopharmaceutical Classification System (BCS) II class drug with weak acidity. The average particle size of IXN-Nps is 249.500 nm, with a polydispersity index (PDI) of 0.149 and a zeta potential of -25.210 mV. The research identified 5 % mannitol as the optimal cryoprotectant. Compared to IXN, the half-maximal inhibitory concentration of IXN-Nps decreased to one-third, demonstrating a significant inhibitory effect on HT-29 colon cancer cells. The in vitro cumulative release rate of IXN-Nps within 24 h was 3.5 times higher than that of the IXN solution. In vivo pharmacokinetic results revealed that the oral bioavailability of IXN-Nps increased significantly by 2.8 times compared to the IXN solution. The correlation coefficient (r = 0.9227) exceeded the critical value for significance at the 0.01 (r = 0.834) level, indicating a strong correlation between in vivo and in vitro results. Consequently, the nanosuspension overcame the low solubility limitation of IXN and proved to be an effective method for enhancing the oral bioavailability of IXN.

Co-Amorphization, Dissolution, and Stability of Quench-Cooled Drug-Drug Coamorphous Supersaturating Delivery Systems with RT-Unstable Amorphous Components

Background: Supersaturating drug delivery systems (SDDSs) have gained significant attention as a promising strategy to enhance the solubility and bioabsorption of Biopharmaceutics Classification System (BCS) II drugs. To overcome challenges associated with polymer-based amorphous SDDS (aSDDS), coamorphous (CAM) systems have emerged as a viable alternative. Among them, "drug-drug" CAM (ddCAM) systems show considerable potential for combination drug therapy. However, many drugs in their pure amorphous forms are unstable at room temperature (RT), complicating their formation and long-term stability profiles. Consequently, limited knowledge exists regarding the behavior of ddCAMs containing RT-unstable components formed via quench cooling. Methods: In this study, we used naproxen (NAP), a RT-unstable amorphous drug, in combination with felodipine (FEL) or nitrendipine (NTP), two RT-stable amorphous drugs, to create "FEL-NAP" and "NTP-NAP" ddCAM pairs via quench cooling. Our work used a series of methods to perform a detailed analysis on the co-amorphization, dissolution, solubility, and stability profiles of ddCAMs containing RT-unstable drugs, contributing to advancements in co-amorphization techniques for generating SDDS. Results: This study revealed that the co-amorphization and stability profiles of ddCAMs containing RT-unstable components produced via a quench-cooling method were closely related to drug-drug pairing types and ratios. Both quench-cooling and incorporation into coamorphous systems improved the dissolution, solubility, and physical stability of individual APIs. Conclusions: Our findings provide deeper insight into the co-amorphization, dissolution, and stability characteristics of specific drug-drug coamorphous systems FEL-NAP and NTP-NAP, offering valuable guidance for developing new ddCAM coamorphous formulations containing some RT-unstable drugs.

Electrospun Amorphous Solid Dispersions with Lopinavir and Ritonavir for Improved Solubility and Dissolution Rate

Lopinavir (LPV) and ritonavir (RTV) are two of the essential antiretroviral active pharmaceutical ingredients (APIs) characterized by poor solubility. Hence, attempts have been made to improve both their solubility and dissolution rate. One of the most effective approaches used for this purpose is to prepare amorphous solid dispersions (ASDs). To our best knowledge, this is the first attempt aimed at developing ASDs via the electrospinning technique in the form of fibers containing LPV and RTV. In particular, the impact of the various polymeric carriers, i.e., Kollidon K30 (PVP), Kollidon VA64 (KVA), and Eudragit® E100 (E100), as well as the drug content as a result of the LPV and RTV amorphization were investigated. The characterization of the electrospun fibers included microscopic, DSC, and XRD analyses, the assessment of their wettability, and equilibrium solubility and dissolution studies. The application of the electrospinning process led to the full amorphization of both the APIs, regardless of the drug content and the type of polymer matrix used. The utilization of E100 as a polymeric carrier for LPV and KVA for RTV, despite the beads-on-string morphology, had a favorable impact on the equilibrium solubility and dissolution rate. The results showed that the electrospinning method can be successfully used to manufacture ASDs with poorly soluble APIs.

Amelioration of tableting properties and dissolution rate of naproxen co-grinded with nicotinamide: preparation and characterization of co-grinded mixture

OBJECTIVE AND SIGNIFICANCE

Reducing the dimensions, when other additives are present, shows potential as a method to improve the dissolution and solubility of biopharmaceutical classification system class II drugs that have poor solubility. In this investigation, the process involved grinding naproxen with nicotinamide with the aim of improving solubility and the rate of dissolution.

METHODS

Naproxen was subjected to co-milling with urea, dimethylurea, and nicotinamide using a planetary ball mill for a duration of 90 min, maintaining a 1:1 molar ratio for the excipients (screening studies). The co-milled combinations, naproxen in its pure milled form, and a physical mixture were subjected to analysis using X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), and solubility assessment. The mixture displaying the highest solubility (naproxen-nicotinamide) was chosen for further investigation, involving testing for intrinsic dissolution rate (IDR) and Fourier-transform infrared spectroscopy (FTIR) after co-milling for both 90 and 480 min.

RESULTS AND CONCLUSION

The co-milled combination, denoted as S-3b and consisting of the most substantial ratio of nicotinamide to naproxen at 1:3, subjected to 480 min of milling, exhibited a remarkable 45-fold increase in solubility and a 9-fold increase in IDR. XRPD analysis of the co-milled samples demonstrated no amorphization, while SEM images portrayed the aggregates of naproxen with nicotinamide. FTIR outcomes negate the presence of any chemical interactions between the components. The co-milled sample exhibiting the highest solubility and IDR was used to create a tablet, which was then subjected to comprehensive evaluation for standard attributes. The results revealed improved compressibility and dissolution properties.

Nutraceutical delivery systems to improve the bioaccessibility and bioavailability of lycopene: A review

Lycopene is a promising biological functional component with various biological activities and excellent pharmacological activities. However, its low water solubility and stability lead to low oral bioavailability, which limits its edible and medicinal research. Then, it is necessary to explore effective methods to protect lycopene from destruction and further exploit its potential benefits. The absorption of lycopene in vivo is affected by solubility, stability, isomer type, emulsifying ability, difficulty in forming micelles in vivo, and interaction with food components. Emulsions, pickering emulsions, micelles, liposomes, bigels, beasds, solid dispersions, microcapsules, nanoparticles, electrospinning and other drug delivery systems can be used as good strategies to improve the stability and bioavailability of lycopene. In this paper, the absorption process of lycopene in vivo and the factors affecting its bioavailability were discussed, and the preparation strategies for improving the stability, bioavailability, and health benefits of lycopene were reviewed, to provide some clues and references for the full utilization of lycopene in the field of health. However, there are still various unresolved mysteries regarding the metabolism of lycopene. The safety and in vivo studies of various preparations should be further explored, and the above technologies also face the challenge of industrial production.

Strategies to improve the stability of amorphous solid dispersions in view of the hot melt extrusion (HME) method

Oral administration of drugs is preferred over other routes for several reasons: it is non-invasive, easy to administer, and easy to store. However, drug formulation for oral administration is often hindered by the drug's poor solubility, which limits its bioavailability and reduces its commercial value. As a solution, amorphous solid dispersion (ASD) was introduced as a drug formulation method that improves drug solubility by changing the molecular structure of the drugs from crystalline to amorphous. The hot melt extrusion (HME) method is emerging in the pharmaceutical industry as an alternative to manufacture ASD. However, despite solving solubility issues, ASD also exposes the drug to a high risk of crystallisation, either during processing or storage. Formulating a successful oral administration drug using ASD requires optimisation of the formulation, polymers, and HME manufacturing processes applied. This review presents some important considerations in ASD formulation, including strategies to improve the stability of the final product using HME to allow more new drugs to be formulated using this method.

Advancement in Solubilization Approaches: A Step towards Bioavailability Enhancement of Poorly Soluble Drugs

A drug's aqueous solubility is defined as the ability to dissolve in a particular solvent, and it is currently a major hurdle in bringing new drug molecules to the market. According to some estimates, up to 40% of commercialized products and 70-90% of drug candidates in the development stage are poorly soluble, which results in low bioavailability, diminished therapeutic effects, and dosage escalation. Because of this, solubility must be taken into consideration when developing and fabricating pharmaceutical products. To date, a number of approaches have been investigated to address the problem of poor solubility. This review article attempts to summarize several conventional methods utilized to increase the solubility of poorly soluble drugs. These methods include the principles of physical and chemical approaches such as particle size reduction, solid dispersion, supercritical fluid technology, cryogenic technology, inclusion complex formation techniques, and floating granules. It includes structural modification (i.e., prodrug, salt formation, co-crystallization, use of co-solvents, hydrotrophy, polymorphs, amorphous solid dispersions, and pH variation). Various nanotechnological approaches such as liposomes, nanoparticles, dendrimers, micelles, metal organic frameworks, nanogels, nanoemulsions, nanosuspension, carbon nanotubes, and so forth have also been widely investigated for solubility enhancement. All these approaches have brought forward the enhancement of the bioavailability of orally administered drugs by improving the solubility of poorly water-soluble drugs. However, the solubility issues have not been completely resolved, owing to several challenges associated with current approaches, such as reproducibility in large scale production. Considering that there is no universal approach for solving solubility issues, more research is needed to simplify the existing technologies, which could increase the number of commercially available products employing these techniques.

The activity and mechanism of vidofludimus as a potent enzyme inhibitor against NDM-1-positive E. coli

New Delhi metallo-β-lactamase-1 (NDM-1) is the most important and prevalent enzyme among all metallo-β-lactamases. NDM-1 can hydrolyze almost all-available β-lactam antibiotics including carbapenems, resulting in multidrug resistance, which poses an increasing clinical threat. However, there is no NDM-1 inhibitor approved for clinical treatment. Therefore, identifying a novel and potential enzyme inhibitor against NDM-1-mediated infections is an urgent need. In this study, vidofludimus was identified as a potential NDM-1 inhibitor by structure-based virtual screening and an enzyme activity inhibition assay. Vidofludimus significantly inhibited NDM-1 hydrolysis activity with a significant dose-dependent effect. When the vidofludimus concentration was 10 μg/ml, the inhibition rate and 50% inhibitory concentration were 93.3% and 13.8 ± 0.5 μM, respectively. In vitro, vidofludimus effectively restored the antibacterial activity of meropenem against NDM-1-positive Escherichia coli (E. coli), and the minimum inhibitory concentration of meropenem was decreased from 64 μg/ml to 4 μg/ml, a 16-fold reduction. The combination of vidofludimus and meropenem showed a significant synergistic effect with a fractional inhibitory concentration index of 0.125 and almost all the NDM-1-positive E. coli were killed within 12 h. Furthermore, the synergistic therapeutic effect of vidofludimus and meropenem in vivo was evaluated in mice infected with NDM-1 positive E. coli. Compared with the control treatment, vidofludimus combined with meropenem significantly improved the survival rate of mice infected with NDM-1-positive E. coli (P < 0.05), decreased the white blood cell count, the bacterial burden and inflammatory response induced by NDM-1-positive E. coli (P < 0.05), and alleviated histopathological damage in infected mice. It was demonstrated by molecular dynamic simulation, site-directed mutagenesis and biomolecular interaction that vidofludimus could interact directly with the key amino acids (Met67, His120, His122 and His250) and Zn²⁺ in the active site of NDM-1, thereby competitively inhibiting the hydrolysis activity of NDM-1 on meropenem. In summary, vidofludimus holds promise as anNDM-1 inhibitor, and the combination of vidofludimus and meropenem has potential as a therapeutic strategy for NDM-1-mediated infections.

Design and Optimization of Rivaroxaban-Cyclodextrin-Polymer Triple Complex Formulation with Improved Solubility

Purpose

This study aimed to ensure the convenience of administration and reproducibility of efficacy, regardless of the meal, by improving the solubility of rivaroxaban (RIV).

Methods

RIV is a non-vitamin K antagonist oral anticoagulants that exhibits a coagulation effect by directly inhibiting coagulation factor Xa. However, RIV has a very low solubility; therefore, it must be administered with a meal at high doses. We used a drug- hydroxypropyl-beta-cyclodextrin (CD)-water-soluble polymer triple complex (R-C-P complex) to solubilize RIV. Using Minitab, we evaluated the effect of each factor on RIV solubility and developed an optimal R-C-P complex formulation. The amount of CD, amount of polymer, and polymer type were set as the independent variables X₁, X₂, and X₃, respectively. RIV solubility (Y₁) and dissolution rate for 45 min in pH 4.5 medium (Y₂) and pH 1.2 medium (Y₃) were set as response variables.

Results

The most efficient RIV solubilization effect was obtained from the composition using CD and HPMC 2208, and physicochemical properties and dissolution parameters were analyzed. RIV in the R-C-P complex was present in an amorphous form and showed high solubility. Unlike commercial products, it showed a 100% dissolution rate. The R-C-P complex formulation secured high RIV solubility and 100% release regardless of pH.

Conclusion

The results imply that high-dose RIV can be administered regardless of the meal, reducing the risk of changing the drug effect due to the patient's administration mistake.

Strategic developments in the drug delivery of natural product dihydromyricetin: applications, prospects, and challenges

Dihydromyricetin (DHM) is an important natural flavonoid that has attracted much attention because of its various functions such as protecting the cardiovascular system and liver, treating cancer and neurodegenerative diseases, and anti-inflammation effect, etc. Despite its great development potential in pharmacy, DHM has some problems in pharmaceutical applications such as low solubility, permeability, and stability. To settle these issues, extensive research has been carried out on its physicochemical properties and dosage forms to produce all kinds of DHM preparations in the past ten years. In addition, the combined use of DHM with other drugs is a promising strategy to expand the application of DHM. However, although invention patents for DHM preparations have been issued in several countries, the current transformation of DHM research results into market products is insufficient. To date, there is still a lack of deep research into the pharmacokinetics, pharmacodynamics, toxicology, and action mechanism of DHM preparations. Besides, preparations for combined therapy of DHM with other drugs are scarcely reported, which necessitates the development of dosage forms for this application. Apart from medicine, the development of DHM in the food industry is also of great potential. Due to its multiple effects and excellent safety, DHM preparations can be developed for functional drinks and foods. Through this review, we hope to draw more attention to the development potential of DHM and the above challenges and provide valuable references for the research and development of other natural products with a similar structure-activity relationship to this drug.

The Influence of the Polymer Type on the Quality of Newly Developed Oral Immediate-Release Tablets Containing Amiodarone Solid Dispersions Obtained by Hot-Melt Extrusion

The present study aims to demonstrate the influence of the polymer-carrier type and proportion on the quality performance of newly developed oral immediate-release tablets containing amiodarone solid dispersions obtained by hot-melt extrusion. Twelve solid dispersions including amiodarone and different polymers (PEG 1500, PEG 4000; PEG 8000, Soluplus^®, and Kolliphor^® 188) were developed and prepared by hot-melt extrusion using a horizontal extruder realized by the authors in their own laboratory. Only eleven of the dispersions presented suitable physical characteristics and they were used as active ingredients in eleven tablet formulations that contain the same amounts of the same excipients, varying only in solid dispersion type. The solid dispersions’ properties were established by optical microscopy with reflected light, volumetric controls and particle size evaluation. In order to prove that the complex powders have appropriate physical characteristics for the direct compression process, they were subjected to different analyses regarding their flowability and compressibility behavior. Additionally, the Fourier transform infrared spectroscopy and X-ray diffraction analysis were performed on the obtained solid dispersions. After confirming the proper physical attributes for all blends, they were processed into the form of tablets by direct compression technology. The manufactured tablets were evaluated for pharmacotechnical (dimensions–diameter and thickness, mass uniformity, hardness and friability) and in vitro biopharmaceutical (disintegration time and drug release) performances. Furthermore, the influence of the polymer matrix on their quality was determined. The high differences in flow and compression performances of the solid dispersions prove the relevant influence of the polymer type and their concentration-dependent plasticizing properties. The increase in flowability and compressibility characteristics of the solid dispersions could be noticed after combining them with direct compression excipients owning superior mechanical qualities. The influence of the polymer type is best detected in the disintegration test, where the obtained values are quite different between the studied formulations. The use of PEG 1500 alone or combined in various proportions with Soluplus^® leads to rapid disintegration. In contrast, the mixture of PEG 4000 and Poloxamer 188 in equal proportions determined the increase in disintegration time to 120 s. The use of Poloxamer 188 alone and a 3:1 combination of PEG 4000 and Soluplus^® also generates a prolonged disintegration time for the tablets.

Enhanced bioavailability and hepatoprotective effect of silymarin by preparing silymarin-loaded solid dispersion formulation using freeze-drying method

This study aimed to develop a solid dispersion formulation of silymarin (Silymarin-SD) using freeze-drying method to enhance its oral bioavailability (BA) by inhibiting the intestinal first-pass effect and increasing its solubility and permeability. Silymarin-SD formulation (i.e., silymarin:tween 80:hydroxypropyl cellulose (HPC) = 1:1:3 (w/w/w) significantly increased silymarin permeability in the duodenum, jejunum, and ileum by decreasing the efflux ratio of silymarin and by inhibiting silymarin-glucuronidation activity, in which tween 80 played a crucial role. As a result, orally administered Silymarin-SD formulation increased plasma silymarin concentrations and decreased silymarin-glucuronide in rats compared with silymarin alone and silymmarin:D-α-tocopherol polyethylene glycol 1000 succinate (1:1, w/w) formulation. In addition to modulating intestinal first-pass effect, Silymarin-SD formulation showed a significantly higher cumulative dissolution for 120 min compared with that of silymarin from the physical mixture (PM) of the same composition as Silymarin-SD and silymarin alone; the relative BA of silymarin-SD increased to 215% and 589% compared with silymarin-PM and silymarin alone, respectively. This could be attributed to the amorphous status of the Silymarin-SD formulation without chemical interaction with excipients, such as tween 80 and HPC. Moreover, the hepatoprotective effect of Silymarin-SD in acetaminophen-induced acute hepatotoxicity, as estimated from the alanine aminotransferase and aspartate aminotransferase values, was superior to that of silymarin. In conclusion, the increase in the dissolution rate and intestinal permeability of silymarin, and the inhibition of silymarin-glucuronidation by the Silymarin-SD formulation, prepared using tween 80 and HPC, increased its plasma concentration and resulted in a superior hepatoprotective effect compared to silymarin.

Review: Liposomes in the prophylaxis and treatment of infectious diseases

Infectious diseases remain as one of the major burdens among health communities as well as in the general public despite the advances in prevention and treatment. Although vaccination and vector eliminations have greatly prevented the transmission of these diseases, the effectiveness of these strategies is no longer guaranteed as new challenges such as drug resistance and toxicity as well as the missing effective therapeutics arise. Hence, the development of new tools to manage these challenges is anticipated, in which nano technology using liposomes as effective nanostructure is highly considered. In this review, we concentrate on the advantages of liposomes in the drug delivery system and the development of vaccine in the treatment of three major infectious diseases; tuberculosis (TB), malaria and HIV.

Development and characterization of solid dispersion-based orodispersible tablets of cilnidipine

Background

Cilnidipine, a calcium channel blocker, is the first-line drug for hypertension and belongs to Biopharmaceutics Classification System II. To mitigate its extensive first-pass metabolism and improve patient compliance, the present study was performed to develop and characterize solid dispersion-based orodispersible tablets.

Results

The phase solubility study with polyvinyl pyrrolidone 15% has shown a 140-fold increase in solubility. X-ray diffraction and differential scanning calorimetry studies emphasized the conversion of solid dispersion from crystalline to amorphous state. Solid dispersion 3 resulted in 142-fold improvement in solubility, 96% of drug content, and percentage drug release was 71.9% at 60 min. F11 containing crospovidone (10 mg) and sodium starch glycolate (16 mg) in combination at higher concentration as super-disintegrants showed the least disintegration time of 26.6 s. In vitro dissolution results are subjected to statistical analysis and found that the formulation (F11) has shown an increased dissolution rate (88.62% at 10 min), compared to the marketed formulation (83% at 60 min).

Conclusions

Solid dispersion prepared by a solvent evaporation method using PVP as a carrier can be utilized for enhancing the solubility of cilnidipine. The incorporation of super-disintegrants in combination improves the dissolution rate of orodispersible tablets. Further, the study can be substantiated by performing stability and in vivo studies in the future.

Graphical Abstract

Solid dispersion technology as a formulation strategy for the fabrication of modified release dosage forms: A comprehensive review

Solubility limited bioavailability is one of the crucial parameters that affect the formulation development of the new chemical entities. Thus the major constraint in the pharmaceutical product development is the suitable solubility enhancement technique for Active Pharmaceutical Ingredient. Solid dispersion (SD) is an established and preferred method for improving the solubility which ultimately may be helpful to enhance bioavailability. For long period of time Amorphous solid dispersion (ASD) have been preferred for improving solubility, but since last two decades, ASD approach have been combined with different modified release approaches to improvise the stability and site specificity of SD to grasp a hold over the specific advantages associated with such dosage forms. It is an established fact now that the SD technique not only improves solubility limited bioavailability, but it may be combined with other approaches to modify the drug release profile from the formulation as per the requirement based on the apt selection of SD carriers and suitable technology. This review covers the comprehensive overview of all such formulations where SD technology is used to serve dual purpose rather than only the sole purpose of solubility enhancement. The SD approach has been successfully implemented for some of the poorly soluble herbal drugs and still there is a vast scope of advancement in that area. The current review will provide a broad outcome in the area of SD technology for modified release formulations along with the description of current status and future prospective of SD. The SD formed by dispersing drug within the conventional carrier to form ASD increases solubility, dissolution rate and bioavailability; whereas fourth generation hydrophobic carriers provide added advantage of controlled release (CR) or sustained release (SR) profile along with enhanced stability of SD. On the other frontier, pH dependant carriers enable the SD to achieve site specificity or delayed release (DR) profile.

Investigating the Potential of Ethyl Cellulose and a Porosity-Increasing Agent as a Carrier System for the Formulation of Amorphous Solid Dispersions

In the present work, an insoluble polymer, i.e., ethyl cellulose (EC), was combined with the water-soluble polyvinylpyrrolidone (PVP) as a carrier system for the formulation of amorphous solid dispersions. The rationale was that by conjoining these two different types of carriers a more gradual drug release could be created with less risk for precipitation. Our initial hypothesis was that upon contact with the dissolution medium, PVP would be released, creating a porous EC matrix through which the model drug indomethacin could diffuse. On the basis of observations of EC as a coating material, the effect of the molecular weight of PVP, and the ratio of EC/PVP on the miscibility of the polymer blend, the solid state of the solid dispersion and the drug release from these solid dispersions were investigated. X-ray powder diffraction, modulated differential scanning calorimetry, and solid-state nuclear magnetic resonance were used to unravel the miscibility and solid-state properties of these blends and solid dispersions. Solid-state nuclear magnetic resonance appeared to be a crucial technique for this aspect as modulated differential scanning calorimetry was not sufficient to grasp the complex phase behavior of these systems. Both EC/PVP K12 and EC/PVP K25 blends were miscible over the entire composition range, and addition of indomethacin did not alter this. Concerning the drug release, it was initially thought that more PVP would lead to faster drug release with a higher probability that all of the drug molecules would be able to diffuse out of the EC network as more pores would be created. However, this view on the release mechanism appeared to be too simplistic as an optimum was observed for both blends. On the basis of this work, it could be concluded that drug release from this complex ternary system was affected not only by the ratio of EC/PVP and the molecular weight of PVP but also by interactions between the three components, the wettability of the formulations, and the viscosity layer that was created around the particles.

Recent advances in the surfactant and controlled release polymer-based solid dispersion

The oral route is the most preferred delivery route for drug administration due to its advantages such as lower cost, improved patient compliance, no need for trained personnel and the drug reactions are generally less severe. The major problem with new molecules in the drug discovery pipeline is poor solubility and dissolution rate that ultimately results in low oral bioavailability. Numerous techniques are available for solubility and bioavailability (BA) enhancement, but out of all, solid dispersion (SD) is proven to be the most feasible due to the least issues in manufacturing, processing, storage, and transportation. In the past few years, SD had been extensively applied to reinforce the common issues of insoluble drugs. Currently, many hydrophobic and hydrophilic polymers are used to prepare either immediate release or controlled release SDs. Therefore, the biological behavior of the SDs is contingent upon the use of appropriate polymeric carriers and methods of preparation. The exploration of novel carriers and methodologies in SD technology leads to improved BA and therapeutic effectiveness. Moreover, the clinical applicability of SD-based formulations has been increased with the discovery of novel polymeric carriers. In this review, emphasis is laid down on the present status of recent generations of SDs (i.e., surfactant and controlled release polymer-based SD) and their application in modifying the physical properties of the drug and modulation of pharmacological response in different ailments.

Preparation of Azithromycin Amorphous Solid Dispersion by Hot-Melt Extrusion: An Advantageous Technology with Taste Masking and Solubilization Effects

Azithromycin (AZI) is one of the most commonly used macrolide antibiotics in children, but has the disadvantages of a heavy bitter taste and poor solubility. In order to solve these problems, hot-melt extrusion (HME) was used to prepare azithromycin amorphous solid dispersion. Preliminary selection of a polymer for HME was conducted by calculating Hansen solubility parameter to predict the miscibility of the drug and polymer. Eudragit^® RL PO was chosen as the polymer due to its combination of taste-masking effect and dissolution. Moreover, the solubility was improved with this polymer. Design of experiments (DoE) was used to optimize the formulation and process, with screw speed, extrusion temperature, and drug percentage as independent variables, and content, dissolution, and extrudates diameter as dependent variables. The optimal extrusion parameters were obtained as follows: temperature-150 °C; screw speed-75 rpm; and drug percentage-25%. Differential scanning calorimetry (DSC) and Powder X-ray Diffraction (PXRD) studies of the powdered solid dispersions showed that the crystalline AZI transformed into the amorphous form. Fourier transform infrared spectroscopy (FTIR) results indicated that the formation of a hydrogen bond between AZI and the polymer led to the stabilization of AZI in its amorphous form. In conclusion, this work illustrated the importance of HME for the preparation of amorphous solid dispersion of AZI, which can solve the problems of bitterness and low solubility. It is also of great significance for the development of compliant pediatric AZI preparation.

Investigation into the role of the polymer in enhancing microwave-induced in situ amorphization

Microwave-induced in situ amorphization is an emerging technology to tackle the persistent stability issue of amorphous solid dispersions (ASDs) during manufacture and storage. The aim of this study was to introduce new effective polymeric carriers with diverse properties to microwave-induced in situ amorphization and to better understand their functions in relation to the final dissolution performance of microwaved tablets. Tablets composed of indomethacin (IND) and different polymers were compacted, stored at 75% relative humidity for at least 1 week and microwaved at 1000 W to induce amorphization. A series of polymers, polyvinylpyrrolidone/vinyl acetate copolymers (PVP/VA) of different monomer weight ratios displaying varyingproperties in functional groupratio, hygroscopicity, molecular weight (M_w), and glass transition temperature (T_g) of the polymer were used as model carriers. The results suggested that more than 90% of IND was amorphized after 20 mins microwaving in all 20% (w/w) drug loaded tablets except for IND:PVAc tablets presenting approx. 36% residual crystallinity. Among them, tablets composed of PVP/VA I-335 and PVP K30 achieved complete in situ amorphization upon microwaving. Further analysis indicated that the influencing factors, polymer M_w and T_g of moisture-plasticized polymer, played a major role in microwave-induced in situ amorphization. In in vitro dissolution study, ASDs containing PVP/VA I-535 with moderate hydrophilicity and 0.96 ± 1.92% IND residual crystallinity showed the most rapid and complete drug release among all formulations, presenting the most promising dissolution performance. Further study on the chemical stability of such formulation showed a statistically insignificant decrease of drug content after pre-conditioning and microwaving (P = 0.288 > 0.05).

Phase transited asymmetric membrane floating nanoparticles: a means for better management of poorly water-soluble drugs

PURPOSE

Effective remedy to gastrointestinal (GI) side effects caused by poorly water-soluble drugs remains a challenge. Researching for novel techniques to reduce these side effects and increase patient adherence to medical treatment is of interest. The current study aims to develop an innovative nano-sized gastro-retentive drug delivery for better management of poorly water-soluble drugs.

METHOD

A non-disintegrating ibuprofen-asymmetric membrane floating nanoparticle (Ibuprofen-AMFNP) was prepared by phase inversion technique to increase the gastric residence of the drug. Powder characterization, solubility, in vitro buoyancy, effect on in vivo inflammatory markers, and polymer diffusibility studies were conducted on the prepared formulation. All UV-spectrophotometric analysis was accomplished through a fiber optic system.

RESULTS

The prepared Ibuprofen-AMFNPs were in the nano range of 114.45 nm ±1.31 nm. The formulation was buoyant for 12 h in the dissolution media indicating increased gastric residence, had better solubility and powder characteristics compared to the pure drug. Scanning electron microscopy revealed an outer non-porous and inner porous asymmetric membrane. Ibuprofen-AMFNP followed Higuchi drug release kinetics (p=0.9925) and had a Fickian diffusion release mechanism (n=0.05). Polymer diffusibility study showed that the 24 h stored formulation had faster drug release with no lag time (-923.08 nm/h) compared to a fresh formulation (2526.32 nm/h). The prepared nano-formulation showed a higher percentage of anti-inflammatory (85.144%) effect compared to the pure drug (78.336%).

CONCLUSION

Ibuprofen-AMFNP is envisioned to help reduce drug-related GI side effects, improve drug delivery, and thereby increase patient adherence to medical treatment.

Exploring the potential of solid dispersion for improving solubility, dissolution & bioavailability of herbal extracts, enriched fractions, and bioactives

Most drugs' poor aqueous solubility has emerged as a significant challenge in achieving proper therapeutic response following oral administration. Herbal drugs are being used from time immemorial to prevent, mitigate, and cure multiple diseases. However, most of the bioactives phytoconstituents possess limited aqueous solubility & poor oral bioavailability. Solid dispersion (SD) has been realised as an efficient formulation to overcome hydrophobic candidates' solubility issues and improve their oral bioavailability. The current review mainly explores the potential of SD for improving solubility, dissolution & bioavailability of herbal extracts, enriched fractions, and isolated bioactives. Hence, basics of SD, selection of excipients, need for SD of plant products, SD of plant products, selection of preparation method, the chemistry of phytoconstituent-excipient interaction, and hurdles associated with SD of herbal extract/enriched fraction were explored in this review. The SD has the potential to overcome solubility, dissolution, and oral bioavailability issues of poorly soluble phytoconstituents.

Dissolution profiles of fenbendazole from binary solid dispersions: a mathematical approach

Aim: Understanding a drug dissolution process from solid dispersions (SD) to develop formulations with predictable in vivo performance. Materials & methods: Dissolution data of fenbendazole released from the SDs and the control physical mixtures were analyzed using the Lumped mathematical model to estimate the parameters of pharmaceutical relevance. Results: The fit data obtained by Lumped model showed that all SDs have a unique dissolution profile with an error of ±4.1% and an initial release rate 500-times higher than the pure drug, without incidence of drug/polymer ratio or polymer type. Conclusion: The Lumped model helped to understand that the main factor influencing the fenbendazole release was the type formulation (SD or physical mixture), regardless of the type or amount of polymer used.

Improved Hygroscopicity and Bioavailability of Solid Dispersion of Red Ginseng Extract with Silicon Dioxide

This study aims to develop a powder formulation for the Korean red ginseng extract (RGE) and to evaluate its in vitro and in vivo formulation characteristics. The solid dispersion of RGE was prepared with hydrophilic carriers using a freeze-drying method. After conducting the water sorption–desorption isothermogram (relative humidity between 30 and 70% RH), differential scanning calorimetry thermal behavior, dissolution test, and intestinal permeation study, a solid dispersion formulation of RGE and silicon dioxide (RGE-SiO₂) was selected. RGE-SiO₂ formulation increased intestinal permeability of ginsenoside Rb1 (GRb1), GRb2, GRc, and GRd by 1.6-fold in rat jejunal segments as measured by the Ussing chamber system. A 1.6- to 1.8-fold increase in plasma exposure of GRb1, GRb2, GRc, and GRd in rats was observed following oral administration of RGE-SiO₂ (375 mg/kg as RGE). No significant difference was observed in the time to reach maximum concentration (T_max) and half-life in comparison to those in RGE administered rats (375 mg/kg). In conclusion, formulating solid dispersion of RGE with amorphous SiO₂, the powder formulation of RGE was successfully formulated with improved hygroscopicity, increased intestinal permeability, and enhanced oral bioavailability and is therefore suitable for processing solid formulations of RGE product.

Diacerein solid dispersion loaded tablets for minimization of drug adverse effects: statistical design, formulation, in vitro, and in vivo evaluation

Diacerein is a BCS class II drug employed in osteoarthritis management. The acid/base hydrolysis of the unabsorbed diacerein in the colon is responsible for its laxative effect. Therefore, this work aimed to enhance the solubility, dissolution, and oral bioavailability of diacerein. Such enhancement means lower doses and fewer gastrointestinal adverse effects. A 4¹.3¹.2¹ full factorial design was adopted to prepare 24 solid dispersion formulae. Solid-state characterization showed the dissolution of diacerein crystals as metastable amorphous or microcrystalline forms in a matrix system that enhanced the drug dissolution. Desirability factor suggested compounding an optimized formula (F1) of Pluronic^®F68 with 1:3 drug:carrier ratio using rotavap that showed higher drug solubility (187.61 µg/mL) than drug powder (22.5 µg/mL). It achieved higher dissolution efficiency (4.04-fold) and rate (6.6-fold) as well as 100% release in 2 min. F1 was compressed into tablets recording greater dissolution efficiency (1.24-fold) and rate (12.5-fold) than the marketed product. The prepared tablet accomplished a 2.66-fold enhancement in diacerein bioavailability compared to the marketed product. In conclusion, the formulation of diacerein as solid dispersion loaded tablets could be of added value for the treatment of osteoarthritis in terms of enhanced patient compliance. Solid dispersion is an easy and scalable technique.

Calcitriol tablets with hybrid lipid-based solid dispersions with enhanced stability and content uniformity

Calcitriol, as the biologically active form of vitamin D3, is essential for patients with renal osteopathy. The solubilization, stabilization, and content uniformity are key issues in its formulation development. In our previous study, the incomplete release of calcitriol was solved by using the hybrid lipid-based solid dispersion (SD) for calcitriol. However, good stability and content uniformity are still urgently needed. In this study, solid lipid with antioxidant properties and liquid lipid compatible with calcitriol were employed as hybrid lipid carrier (HLC) to establish a solid dispersion. Moreover, the content uniformity of tablets with hybrid lipid carrier based SDs (HLCTs) was further guaranteed due to the multi-dispersion of calcitriol in HLC, solidification, and blank granules. Additionally, the compression of the blank granules was adjusted by the water content. The mixing method of calcitriol-containing and blank granules was also optimized. The obtained HLCTs were evaluated for hardness, disintegration time, in vitro drug dissolution, content uniformity, and stability. Satisfactory HLCTs were developed successfully in this study with superior content uniformity and better stability than the commercial soft capsule (Rocaltrol®). It was proved to be a promising formulation for drugs with poor water-solubility, instability to oxygen and heat, and dose-related toxicity.

Albendazole solid dispersions against alveolar echinococcosis: a pharmacotechnical strategy to improve the efficacy of the drug

Alveolar echinococcosis is a neglected parasitic zoonosis caused by Echinococcus multilocularis. The pharmacological treatment is based on albendazole (ABZ). However, the low water solubility of the drug produces a limited dissolution rate, with the consequent failure in the treatment of the disease. Solid dispersions are a successful pharmacotechnical strategy to improve the dissolution profile of poorly water-soluble drugs. The aim of this work was to determine the in vivo efficacy of ABZ solid dispersions using poloxamer 407 as a carrier (ABZ:P407 solid dispersions (SDs)) in the murine intraperitoneal infection model for secondary alveolar echinococcosis. In the chemoprophylactic efficacy study, the ABZ suspension, the ABZ:P407 SDs and the physical mixture of ABZ and poloxamer 407 showed a tendency to decrease the development of murine cysts, causing damage to the germinal layer. In the clinical efficacy study, the ABZ:P407 SDs produced a significant decrease in the weight of murine cysts. In addition, the SDs produced extensive damage to the germinal layer. The increase in the efficacy of ABZ could be due to the improvement of water solubility and wettability of the drug due to the surfactant nature of poloxamer 407. In conclusion, this study is the basis for further research. This pharmacotechnical strategy might in the future offer novel treatment alternatives for human alveolar echinococcosis.

Orodispersible films containing ball milled aripiprazole-poloxamer®407 solid dispersions

This research aimed at developing ODFs containing an antipsychotic drug - aripiprazole (ARP). ARP, as a BCS II class molecule, requires enhancing its water solubility prior to formulating. Therefore, a solid dispersion of ARP - Poloxamer® 407 was prepared by ball milling, then incorporated into the films. It was found that co-processing led to an over 100-fold increase in drug solubility in comparison with pure drug. Moreover, ODFs with solid dispersion showed faster drug release (>95% below 15 min) and disintegration (<30 s), compared with raw ARP films. These results are believed to be due to the solubilization effect of poloxamer and enhanced wettability of the film. Films containing solid dispersions were found to possess smoother film surfaces and favorable mechanical properties - flexibility and strength. The ODF formulations, prepared by a casting method, were based on three different polymers (Kollicoat® IR, Kollicoat® Protect or PVA). It was found that not only the form of the incorporated drug, but also the type of film-forming polymer had an impact on the analyzed parameters. The use of PVA was beneficial in the film formulation with aripiprazole in comparison to other tested film-forming polymers.